Making Space for the Chimpanzees of Bossou
WORDS BY MAXWELL WILLIS.
From Living at the Interface: Human-Chimpanzee competition, coexistance and conflict in Africa by Kimberly J Hockings (map provided by N. Granier)
In what sort of space can you find a chimpanzee? Perhaps in a secluded corner of an African jungle, several hours hike from the nearest town? This would certainly be true for chimpanzees in spaces such as Kibale Forest in Uganda, a protected rainforest 766 sq km in size, over 2 hours hike from the nearest town. Inhabited by over 1500 chimpanzees, Kibale is home to one of the highest populations of primates in Africa.
A 2021 article published in the Conservation Science and Practice journal, found that larger spaces generally support larger chimpanzee populations. Larger spaces provide a higher quantity of food, space for nesting sites, and territories for competing families. The same article also found animal populations are generally higher in spaces sequestered from human activity, where the effects of poaching and habitat disturbance are reduced.
However, the Bossou Hills Reserve in Guinea, West Africa, is home to a group of chimpanzees that have defied all odds. A modest 7 sq km in size, the space is a protected area of rainforest located at the southern end of Bossou town. Despite frequent interaction with the 10,000 residents of Bossou, and confinement to a space dwarfed by the likes of Kibale, Bossou Hills is home to a population of chimpanzees, albeit a modest 10-25 individuals in size. A 2016 paper by Nicolas Granier suggests the survival of the Bossou chimpanzees may owe, at least in part, to their devout protection by the residents of Bossou.
Research on the Bossou chimpanzees was initiated in 1976 by biologist Yukimara Sugiyama of the Primate Research Institute of Kyoto University, Japan. In the decades since, the Bossou chimpanzees have been studied by researchers from around the world, as a unique example of an environment where chimpanzees have shared an intimate space with humans for several generations.
However, an intimate sharing of space can result in frequent attacks. A 2010 paper published in the American Journal of Primatology (Am. J. Primatol.) indicates nine people per year are attacked by chimpanzees and baboons in Uganda. However, the same paper indicates chimpanzee attacks are relatively rare in Bossou, despite an intimate sharing of space. Fewer than one attack per year has been reported since 1995. In his 2016 paper, Nicolas Granier suggests this stems from a tradition maintained by the people in Bossou where chimpanzees are believed to be sacred animals; harassment or poaching of chimpanzees is forbidden by traditional law.
Prevention of acts of aggression towards chimpanzees over several generations may account for the lack of fear displayed by chimpanzees in the presence of humans. The 2010 paper published in Am. J. Primatol. found that chimpanzees are likely to attack humans, only if they are deemed a threat. As such, prevention of acts of aggression towards chimpanzees subsequently prevents humans from being attacked by chimpanzees.
A 2015 paper published in the Am. J. of Primatol. indicated protection of the Bossou chimpanzees may fall short of securing their future indefinitely. The modest size of the Bossou space will restrict the population size to the extent that chimpanzees will mate with close relatives – a process known as ‘inbreeding’. When animals mate, the offspring receives a gene from each parent. Close relatives are likely to share similar DNA, including genes that may result in disease. Thus, mating between close relatives increases the risk of the offspring receiving a harmful gene. A 2018 paper published in the Evolutionary Applications journal found the effects of inbreeding can be so detrimental to the health of a population as to place it at risk of extinction.
Consequently, contemporary work for the Bossou chimpanzees aims to create a protected corridor of rainforest between Bossou Hills and nearby rainforest. The 2015 paper published in Am. J. Primatol. suggests an expansion of habitat space will allow the population to grow in size and provide opportunity for chimpanzees to breed with unrelated mates. As such, it appears survival of the Bossou chimpanzees in the long term will require modern conservation practice and traditional customs to be applied together.
EDITORIAL NOTE: This article has been reuploaded and was originally published in 2023.